Re: [2.6.20][PATCH] fix mempolicy error check on a system with memory-less-node

[Andi Kleen <ak@suse.de>]

On Wednesday 07 February 2007 17:23, Andrew Morton wrote:
> On 07 Feb 2007 11:20:06 +0100 Andi Kleen <ak@suse.de> wrote:
> 
> > KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> writes:
> > 
> > > current mempolicy just checks whether a node is online or not.
> > > If there is memory-less-node, mempolicy's target node can be
> > > invalid.
> > > This patch adds a check whether a node has memory or not.
> > 
> > IMHO there shouldn't be any memory less nodes. The architecture code
> > should not create them. The CPU should be assigned to a nearby node instead.
> 
> umm, why?
> 
> A node which has CPUs and no memory is obviously physically possible and
> isn't a completely insane thing for a user to do.  I'd have thought that
> the kernel should be able to cleanly and clearly handle it,

It doesn't.

> and to 
> accurately present the machine's topology to the user without us having to
> go adding falsehoods like this?

a node is a piece of memory. Without memory it doesn't make sense.

-Andi